The Tennessee Aquarium is one of the world's largest freshwater aquariums, and easily Chattanooga's biggest attraction, contributing more than $115 million to the city's economy annually.
At the Aquarium, the octopuses are given puzzles to solve such as a lidded jar with a piece of food inside. They quickly learn to unscrew the tops of the jars to get to the food inside.
Both are great interactive experiences for children & aquatic life. If you have to choose between the 2 I would probably say visit the GA Aquarium, but I live in Atlanta & still take my kids to the TN Aquarium when we are in Chattanooga.